Devices that have removable battery packs, such as laptop computers, personal audio and video players, etc., most often have two power input jacks. The first power-input port is obvious . . . it is where the connector from the external wall adapter, AC/DC power-conversion adapter, DC/DC automotive cigarette-lighter adapter, external battery charger, etc., is plugged in.
The second power-input port is not so obvious . . . it is where a removable battery pack connects to its associated host device. Usually, this is a power (or mixed-signal power and data) connector hidden in a battery bay, or expressed as a cord and connector inside a battery compartment, such as is found in some cordless phones. The connector between a battery pack and its associated host device may simply be a group of spring contacts and a mating set of contact pads. This second power port is not used for external power (a host's removable battery power source is usually not classified as “external” power). The battery power port is so unrecognized that even supplemental external “extended run-time” battery packs, as are available from companies like Portable Energy Products, Inc. (Scotts Valley, Calif.), connect to the same traditional power jack to which the external power supply does.
The connector assembly herein exploits this un-utilized battery-to-host interface in a number of ways. As will be seen, a battery pack's power port is, in many ways, a far more logical power interface than the traditional power-input jack. By using a flexible and scaleable connector that is small enough to be enclosed within a battery pack housing, and providing sufficient connector contacts to handle power, the usefulness of external power devices and the battery pack itself can be enhanced.
Also, “smart” battery packs support connectors that are mixed signal, i.e., both power and data, therefore external power devices can data communicate with host devices and smart batteries, often facilitating device configuration, operation and power monitoring.
Some of the reasons why the battery-contact interface isn't used are that it's often inaccessible. In laptop computers, for example, the battery-to-host-device connector is often buried deep in a battery bay. The connector assembly described in this document is built into the battery pack itself, at a location where easy access to a connector is available. Where appropriate, conductors from a non-removable battery are routed to an accessible location on the host device. Even when the location of the connector assembly is remote from the battery pack, the interface addressed is that between the battery pack and its associated connector on the host device.
Another reason for the lack of attention to the battery's power connector is that the type of connector used between a battery and its host device is not usually of the design and style that would easily lend itself to being attached to the end of a power cord. A good example of how awkward such battery access connectors can be is the “empty” battery housing with power cord that is popular with camcorders. The camcorder's “faux” battery pack shell snaps into the normal battery pack mount, and there is usually a hardwired cord to a power-conversion adapter. This makes for a considerable amount of bulky goods to transport. That is the case with cellular phones, as well, with “empty” battery housings that plug into an automotive cigarette lighter, or a battery pack with an integrated charger. These are often bulkier than the battery pack they replace and, almost always, one must have a unique assembly—complete with cords—dedicated to a specific make or model of cellular phone.
The connector assemblies shown in the various figures, and described herein, are designed to be of the look and style normally associated with power and or data cords. Barrel-style connectors, and segmented-pin-types are common connector styles. By defining new barrel connectors that feature segmented contacts, or using segmented pin connectors in wiring schemes that create new connectivity paths, hitherto unknown ways of dealing with safety through power sub-system configurations are achieved. No bulky external add-ons are used. Instead, miniaturized connectors that can be embedded within an existing battery pack define new ways of powering battery-powered devices.
The battery packs discussed here are not empty battery enclosures, with only passthrough wiring. The original battery cells, circuit boards, fuses, etc., are all present and the connectors shown herein provide means to have a battery pack operate normally when the plugs are removed (or replaced).
Battery Pack Removal
Another reason a battery port connector is not used is that to access this unexploited power port would require removing the battery pack, which would result in the loss of available battery power. Some host devices require that a battery pack be present, as the battery may be serial-wires. Also, host devices are known that use the battery pack as a “bridge” battery that keeps CMOS, clocks, etc., functioning. Battery removal could negatively impact such devices. Removing a battery pack also results in even more bulky things to carry around, which hardly fits the travel needs of someone carrying a laptop or other mobile device.
By embedding connectors in the battery pack, no circuits are created within the host devices. This is useful because battery packs are virtually always removable and replaceable. Instead of having to pre-plan and design-in new power and data paths into a host device, the replaceable battery pack contains these power and data paths. Simply replacing a battery pack upgrades any host device. By placing the technology in a fully-functional battery pack, it is not necessary to remove the battery pack during connector operations . . . instead, keeping the battery pack in its host device, where it belongs, is essential.
Devices that use external power-conversion adapters invariably are designed to always charge the device's removable battery pack every time the external adapter is used. It seems logical that keeping the battery capacity at 100% is a sound practice. However, certain rechargeable battery chemistries don't offer the charge/recharge cycle life that was available with “older” battery technologies. Lithium-Ion (Li-Ion) batteries, for example, can last for only 300 cycles, and sometimes even less than that. In average use, an Li-Ion battery can have a useful life (full run-time, as a function of capacity) of less than a year, and nine months isn't uncommon. Constantly “topping-off” a Lithium-Ion battery only degrades useful battery life.
Being able to elect when to charge the battery, independent of powering the host device, would prolong the life of expensive batteries. By delivering power from external power adapters and chargers through connectors at a newly-defined battery power port, a user need only perform a simple act, such as rotating a connector to select a battery-charge; mode, a host-power only mode, or both.
Battery Charging Risks
Battery charging is a destructive process in other ways than repeated unnecessary battery charging sessions. Low-impedance batteries, such as Lithium-Ion, generate heat during the charging process. This is especially true if a cell-voltage imbalance occurs for, as resistance increases, the entire battery pack can overheat. Lithium-ion cells have a reputation for volatility. For example, an article in the Apr. 2, 1998, edition of The Wall Street Journal reported on the potentials of fire, smoke and possible explosion of Li-Ion batteries on commercial aircraft (Andy Pasztor, “Is Recharging laptop in Flight a Safety Risk?,” The Wall Street Journal, Apr. 2, 1998, pp. B1, B12).
To be able to easily disengage a volatile battery cell cluster from its integrated, hardwired battery charging circuit has obvious safety benefits. Several of the modalities of the connector assemblies discussed herein lend themselves to a simple battery bypass circuit within the battery pack, so that a host device can be powered from an external power source such as an aircraft seat-power system, without charging the battery. This function is achievable by simply replacing an existing battery pack with one that incorporates the connector assembly. This is a cost-effective, simple and convenient solution to an important safety concern. Because the connector assembly is a modification to an existing battery pack, and battery products already have a well-established and wide distribution network, availability of this safety device is widespread. No entirely new devices are required to be designed and fabricated, since the connector assembly is essentially an upgrade modification.
Power-Conversion Adapters
Battery flammability and explosive volatility are related to inappropriate power devices upstream of the battery pack. Connecting a power-conversion adapter that has an output voltage not matched to the input voltage of a host device is an easy mistake to make. Laptop computer input voltages, for example, can range from 7.2 VDC, to 24 VDC. Within that voltage range are a significant number of AC/DC and DC/DC adapters that are power-connector-fit compatible, but which output incompatible voltages. A count of notebook computer power-conversion adapters available from one mail order company numbered over 250 discrete products (iGo, Reno, Nev., www.iGoCorp.com). The probability of a voltage mismatch indicates a serious concern.
Compared to the multiplicity of vast and diverse input voltages battery-powered host devices require, input voltages at battery power ports are not only limited, but more flexible. Since battery output voltages are a function of an individual cell voltage, multiplied by the number of cells wired in series or parallel, there are a limited number of output voltages for battery packs. For example, Lithium-Ion cylindrical cells are manufactured at only 3.6-volts (some are 4.2-volt cells). Thus, virtually every Li-Ion battery pack made outputs either 10.8, or 14.4 volts (with some relatively rare 12.6-volt cell clusters). If an external power-conversion adapter was designed to provide power to a notebook computer host device through the host device's battery port, it is possible that only two output voltages would be required, since the external adapter would electrically “look” to a host device as a battery pack. This adds value to a connector assembly that can eliminate the problem of there being some 42 different types of existing laptop power connectors.
Furthermore, battery pack output voltages vary as a function of charge state. A fully charged battery rated at 10.8-volts actually outputs voltages in a range from about 10-volts, through 14.0-volts (with transient voltages up to 16 volts), depending on the battery's state of charge or discharge. This same host device may be able to accept input voltages at its usual external power-adapter input port within a narrow voltage range of +/−1-volt. Thus, host devices have a far greater tolerance for potential voltage mismatches at their battery power ports, as compared to at the traditional power jack. By providing a power connector that uses the battery's power port, the number of external power devices is significantly reduced, and the overall risk of damaging a host device by a voltage mismatch is minimized.
The heat dissipation from charging a Lithium-Ion battery pack is compounded by the heat being generated by advanced high-speed CPUs. With computer processors running so hot in portable devices that heat sinks, fans, heat pipes, etc., are required, the additional heat from charging a battery only intensifies the thermal issues.
The connector assembly described herein, by disengaging battery charging, extends the life of a host device's components and circuits that otherwise may be compromised or stressed by extended hours of exposure to heat. This is especially valid for host devices like laptop computers, since a number of these products are not used for travel, but instead spend almost all of their useful lives permanently plugged into the AC wall outlet in a home or office, serving as a desktop substitute. In such device applications, the need to repeatedly charge the laptop's battery has no practicality. By using a connector assembly that can be selectively put into a mode of battery charging only when necessary, the working life expectancy of these host devices can be extended by eliminating unnecessary overheating.
Energy Conservation
There's a less obvious reason to not charge batteries on commercial aircraft. Some commercial passenger aircraft provide power systems with power outlets at the passenger seat. The head-end aircraft power source is a generator, so the total amount of energy to power all of the aircraft's electrical system is limited. The Airbus A319, for example, has only sufficient generator capacity to provide seat power for less than 40 passengers' laptop computers (Airbus Service Information Letter (SIL), dated 8 Jan. 1999). A laptop computer being powered from an external power-conversion adapter uses 20-40% of the external power to charge its battery pack, which translates to about 15-30 Watts. Generating sufficient power to charge 200+ laptop batteries puts a considerable drain on the aircraft's electrical system.
Disabling battery charging by employing a connector assembly described herein is a cost-effective means of lowering an airline's operating costs, by minimizing the total load schedule of the cabin power grid. The airline saves the cost of the fuel required to operate the generator at a higher power capacity.
Airline operators have policies and in-flight rules that prohibit the types of passenger electronic devices that can legally operate on the plane. The use of RF devices, such as cellular phones, and radio-controlled toys, is banned on every commercial aircraft. Passengers may be confused on aircraft operated by American Airlines, for example, since selected passenger seats have power systems for laptop use. This airline's seat power outlet is a standard automotive cigarette-lighter port. An unsuspecting passenger, mistakenly assuming that the cigarette-lighter port was for cellular phones, could easily plug in and turn on a cell phone.
Because there are a number of modalities to the connector assembly described in this document, airlines can elect to use a specific connector style, shape or wiring scheme that is reserved for passenger seat-power. By limiting the use of a receptacle to battery packs for laptops, and not allowing the connector to be used in cellular phone battery packs, for example, an airline can control the types of passenger devices it allows to be connected to its cabin power system.
Battery-Only-Powered Devices
There is also a variety of battery-powered devices that does not have an external power-supply power input jack. Cordless power tools, flashlights, and other devices meant to run strictly on removable and/or externally rechargeable batteries may not have been manufactured with an alternative means of power. If the battery of a cordless drill goes dead, for example, the only recourse is usually to remove the battery and recharge it in its external charger. This is frustrating to anyone who has had to stop in the middle of a project to wait for a battery to recharge.
By integrating a new connector assembly, such as the ones shown in the figures and text herein, circuits can be created that use a host device's battery-power-port interface as a power connector through which power can be delivered from an external power source. A user can elect, when a power outlet is available, to operate devices such as battery-powered drills, saws, etc., from external power, simply by attaching a compliant external power adapter into the connector interface on an exposed face of the battery pack. With some modalities of the connector assembly that is the invention, an external charger can be connected as well, allowing simultaneous equipment use and battery charging in products that hitherto did not have these capabilities.
Devices with holders for individual battery cells fall into this same category of not having an external power port. If the device does have an external port, it is not wired to provide simultaneous battery charging. Not being able to charge replaceable battery cells in a battery holder that is inside the host device lessens the usefulness of rechargeable alkalines, for example.
It is more convenient to leave individually replaceable battery cells in their battery holder while charging, and a number of the modalities of the connector assembly discussed herein allow for that. The added convenience of being able to operate a host device instead of draining its rechargeable alkalines (these battery types typically can only be recharged 10-20 times, then must be discarded), reduces operating costs. The use of the connector assembly saves time, since the user doesn't have to take the time to remove each individual cell and place it in a special charger.
Operational Advantages
Given the above, a number of operational advantages of the connector assembly of the invention become apparent:                (a). A simple, low-cost connector can be used to electrically separate two devices, or a host device and its power system.        (b). By isolating the battery source, or a peripheral, from the original host device, new circuits are created that allow external power sources or battery chargers to perform more safely because the battery voltage can be verified before that external power is applied to a host device.        (c). Because a plug can function as a rotating selector switch that has more than one position, additional circuits or wiring configurations can be created to perform specialty functions or operations.        (d). As a “key,” part of a male connector can be removable and interchangeable at the end of a power or data cord, to afford access control to equipment or electronic devices.        (e). With its very small form factors, a female connector can be embedded inside a battery pack, to make it a self-contained device that has a special power or data interface to external power or charging devices, or monitoring equipment. This can be accomplished without having to rewire or otherwise modify a host device. By replacing the existing battery pack with one configured with a connector assembly that is the invention, the functionality of both a battery and its host device is enhanced, without permanent reconfigurations to either the battery pack or host device.        (f). The connector assembly can be used as a replacement for an existing input power jack, with minimal modifications or rewiring.        (g). Problems with the existing multiplicity of connectors on electronic devices that allow incompatible external adapter output voltages are eliminated. Instead, the receptacle is simply wired in a different configuration, and a new plug is used to differentiate the two incompatible external adapters. Any fear of possible mismatched voltages between external power adapters and host devices is eliminated.        (h). In certain embodiments of the connector assembly that use a female connector that self-closes to reinstate a circuit, the need for an ON/OFF power switch in conjunction with a power input jack is eliminated. A plug is now defined that is configurable to turn the host device on when the plug is inserted into the receptacle.        (i). Certain embodiments of the connector assembly can be equipped with a latching mechanism that secures the plug and receptacle assemblies, an important feature for devices like laptops that are often moved around the local area in industrial or service applications.        (j). In certain environments, host devices that automatically charge their batteries when external power is applied can be easily modified by inserting a battery pack that has been upgraded to the connector assembly in this invention. Thus configured, the host device is rendered safety compliant.        (k). Simultaneous battery monitoring and power delivery from an external device can be done without modifying the internal circuitry of the host device.        (l). By installing a switch that responds to applied power signals, and locating that switch in either the plug or receptacle assemblies of the connector, battery monitoring and power delivery can occur with a two-conductor cable that shares more than two contacts in a connector assembly.        (m). Monitoring battery charging can be done by an external device attached to a connector assembly such as those defined herein, which may be capable of power, data, or both.Applications        
An upgraded battery pack that creates different electrical paths for power, data, or both when a plug is inserted or removed may, for example, include applications such as (but not limited to) the following:                1) Diminish the need to be charging a battery pack when an external power source is available. By not charging a battery every time a host device is connected to an external source of power, the life expectancy of the battery is increased. Since most rechargeable battery-powered electronic devices automatically charge their batteries when external power is connected, the use of a connector that disables the battery charge function increases the useful life of the battery, thus reducing total operating cost.        
2) Some locations may not find battery charging practical. Battery charging can consume 20-40% of the entire load schedule of a host device's power requirements. If a car's battery is low, operating a host device such as a laptop for an extended time from the dashboard outlet could result in a stranded motorist.                3) Some transportation locations may not be suitable for battery charging. There is some risk in charging batteries, especially high-density Lithium-Ion batteries. An airline, or cruise ship operator, for example, may wish to limit the risk of an onboard battery-related fire or explosion. A simple and cost effective method would be to use battery packs and power cords that have a connector which disables the charge function, while still allowing an external power supply to power the host device only.        4) Extended-run-time external battery packs can be used to supplement a host-device's associated battery. These extra-high-capacity battery packs connect to a host device's existing power input jack. So configured, the external battery pack most likely is dedicating some of its stored energy to charging the host device's battery. This occurs because host systems are designed to charge the associated battery whenever external power is available.                    As a power source, a host device usually does not distinguish an external battery from an AC/DC wall adapter, for example, so the extended-run-time battery loses its effectiveness by having to relinquish some amount of its stored energy to charging the host's battery. By using a connector as defined herein, the external battery pack can be routed through the host device's existing battery pack and, by doing so, the charging circuits with the host device are temporarily disabled while the external battery source is in use. This enhances the run-time of the external battery pack, and also eliminates inefficient energy transfers between the two batteries.                        
These non-limiting examples of applications for connector assemblies such as those described in this document show some practical real-world uses.
Design Parameters
Some of the design parameters required to achieve these uses may be:                1) Small package size, especially for the receptacle, since available space within battery packs is limited.        2) Straightforward way to integrate a female connector into an existing battery pack, or to install the receptacle in a new battery pack design in a way that doesn't require an inordinate amount of extra tooling or assembly.        3) Inexpensive        4) Simplicity of use        